Acacia Farnesiana Research Articles

Branch Girdling and Oviposition Biology of Oncideres pustulatus (Coleoptera: Cerambycidae) on Acacia farnesiana

Female Oncideres pustulatus LeConte girdle Acacia farnesiana (L.) Willd. branches to provide a suitable host for their progeny. After girdling a branch, eggs are laid in the girdled section where the hatching larvae feed beneath the bark. Girdled branches were 13-55 mm in diameter and up to 4.01 m in length. Females contained as many as 63 mature eggs, but oviposition averaged 312 eggs per branch; a maximum of 2,898 eggs was laid on a single branch. A multiple regression analysis indicated that branch volume, number of lateral branches, and branch surface area were significant variables accounting for the variation in egg numbers per branch (r2, 0.806). Larvae consumed an average of 9.3 cm3 of wood from the girdled branches, but high oviposition densities within a branch forces larvae to compete for the limited resource. When one female begins girdling a branch, other females oviposit on the branch without assisting in the girdling. Potential reproductive strategies by girdling and nongirdling females are discussed.

Seed Germination Characteristics of Selected Native Plants of the Lower Rio Grande Valley, Texas

Experiments were conducted to identify treatments that increased emergence of seeds of 24 woody plant species native to the lower Rio Grande Valley of southern Texas. Sulfuric acid (18.4M H2S04) scarification signiflcantly increased emergence of huisache (Acacia smallii), huisachillo (A. schqffneri), Texas ebony (Pithecellobiumflexicaule), tenaza (P. pallens), tepeguaje (Leucaenapulverulenta), retama (Parkinsonia aculeata), and western soapberry (Sapindus drummondii); treatments such as soaking in distilled water, gibberellic acid (0.3 or 1.4 mMol), or other scarification techniques were not as effective as acid. Fresh guajillo (A. berlandieri) seeds required no treatment, but 8-month-old seeds had higher emergence with acid scarification. Texas ebony emergence was higher from 10-month-old seed treated with acid than from fresh seeds. No pre-treatment seemed necessary for seeds of coral bean (Erythrina herbacea), Texas persimmon (Diospyros texana), sugarberry (Celtis laevigata), granjeno (C. pallida), pigeon-berry (Rivina humilis), Texas baby-bonnets (Coursetia axillaris), guajillo (A. berlandieri), and lotebush (Ziziphus obtusifolia). Results with blackbrush (A. rigidula), Wright's acacia (A. wrightii), rattlebush (Sesbania drummondii), guayacan (Guaiacum angustifolium), brasil (Condalia hookeri), elbowbush (Forestiera angustifolia), and anacua (Ehretia anacua) seeds were inconclusive. Plants of 16 woody species achieved mean heights of 25 cm in 45 to 150

Tebuthiuron Formulation and Placement Effects on Response of Woody Plants and Soil Residue

Tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} in various formulations and placements was applied to honey mesquite (Prosopis glandulosaTorr. # PRCJG), huisache [Acacia farnesiana(L.) Willd. # ACAFA], live oak (Quercus virginianaMill.#QUEVI), Macartney rose (Rosa bracteataJ. C. Wendl. # ROSBC), and Texas whitebrush [Aloysia gratissima(Gillies & Hook.) Troncoso # ALYLY]. There was little difference in a species response to the various tebuthiuron formulations. Pellets (20%) at 2 g ai/tree base reduced the canopy 85% and killed 50% of the honey mesquite. At 1 g ai/plant, two briquettes at 0.5 g ai each or pellets (5.14 g, 20%) killed 37 and 80% of the huisache, respectively. Pellets were no more effective at 2 g than at 1 g ai on huisache. Basal treatments of 0.25, 0.5, 0.5, 1, and 2 g ai tebuthiuron/tree killed from 8 to 22, 48 to 62, 62 to 85, and 92% of the live oak, respectively. Pellets at 2 g ai placed at the base reduced the canopy 83% and killed 59% of the Macartney rose. On Texas whitebrush, 0.25, 0.5, 1, and 2 g ai tebuthiuron/tree killed from 68 to 85, 75 to 100, 90, and 100% of the plants, respectively. Tebuthiuron persisted mainly in the upper 30 cm of soil for at least 15 months.

Detecting Huisache (Acacia farnesiana) and Mexican Palo-verde (Parkinsonia aculeata) by Aerial Photography

Huisache [Acacia farnesiana(L.) Willd. # ACAFA] and Mexican palo-verde (Parkinsonia aculeataL. # PAKAC) are native woody legumes that often occur together on rangelands of southern Texas and northern Mexico. Huisache produces a profusion of orange-yellow flowers during February or March giving it a conspicuous golden appearance. Mexican palo-verde produces a heavy bloom of yellow flowers in mid-April or early May giving it a yellow-green coloration. Plant canopy light reflectance measurements of flowering huisache showed that its reflectance at the 0.55- and 0.65-μm visible wavelengths was significantly higher than that of Mexican palo-verde in the vegetative stage and four other associated plant species or mixture of species. Conversely, reflectance measurements of flowering Mexican palo-verde showed that its reflectance at the 0.55-μm visible wavelength was significantly higher than that of huisache in the vegetative stage and the same four associated plant species or mixtures of species. Flowering huisache had a golden color on conventional color (0.40-to 0.70-μm) aerial photos that made it distinguishable from other plant species, whereas flowering Mexican palo-verde had a pink image on color-infrared (0.50- to 0.90-μm) aerial photos. However, immature plants of both species cannot be detected using this technique. Computer-based image analyses of conventional color film positive transparencies showed that huisache infestations could be quantified from associated rangeland species. This technique can permit ‘percent land area infested’ estimates of mature huisache on rangelands. These results show that aerial photography may be a useful tool to detect and monitor the spread of huisache and Mexican palo-verde on rangelands, and to delineate areas needing control.

Homogeneous alkylcysteine lyase of Acacia farnesiana: Fresh seedlings vs. acetone powders

Alkyleysteine lyase (EC 4.4.1.6) was purified essentially to homogeneity from both fresh hypocotyls of 5- to 8-day-old etiolated seedlings of Acacia farnesiana and acetone powders of such hypocotyls. The enzyme from the fresh material had twice the specific activity of that from the acetone powder. Sodium dodecylsulphate gel electrophoresis showed that both enzymes were composed of a subunit of M r ca 42 000. The final enzyme solutions were quite different in their absorbance spectra. The fresh hypocotyl enzyme had an absorbance maximum at 425 nm in addition to the 280 nm protein absorbance. This maximum in the visible region is due to bound pyridoxal phosphate. The acetone powder enzyme had the same maxima and in addition peaks at 498 and 340 nm. The fresh enzyme contained 1.8 mol cofactor/mol enzyme and the acetone powder enzyme 1.0 mol/mol. The KK m for the probable natural substrate L-djenkolate was the same for both enzymes, 0.8 mM, but the V max for the fresh was twice that of the acetone powder enzyme. The common practice of using acetone powder preparations for starting material in enzyme purifications would appear to require some caution.

Changes in Nitrogen, Carbon, and other Surface Soil Properties During Secondary Succession

AbstractSoils were analyzed from 10 river terrace plant communities ranging in age from 5 yr to more than 150 yr. Soil C and N concentrations increased significantly with plant community development up to 25 yr. When quadratic transformations were used, soil N accretion was correlated with huisache (Acacia smallii Isely) stem basal area. Texas sugarberry (Celtis laevigata Willd.) basal area was correlated with the soil N concentration and soil C accretion was correlated with total community basal area. Plant community development (measured as basal area) was examined using stepwise multiple linear regression analysis. Seventy‐six percent of the variance of huisache basal area could be explained by community age, soil N, K, Mg, and silt content. Seventy‐seven percent of the variance of Texas sugarberry basal area could be explained by community age, soil N, Mg, and clay content. Ninety‐one percent of the variance in total community basal area could be explained by community age, soil pH, N, and clay content. Changes in other soil chemical and physical properties occurred during succession and may be important in determining community species composition and structure.

Methods of Enhancing Germination of Anacua Seeds

Seed dormancy hampers establishment of anacua [Ehretia anacua (Teran & Berl.) I.M. Johnst.] in plantings for wildlife. We evaluated methods of enhancing anacua germination and causes of dormancy. Seeds were (1) scarified with 2.9 mol liter -' H202 or 0.71 mol liter' NaOCl for 10, 20, or 30 minutes, or concentrated (18.0 mol liter-) H2SO4 for 15, 30, 60, or 120 minutes; (2) rinsed with water for 12, 241 36, and 48 hours; (3) treated with 0.1, 1.4, 2.9, and 4.3 mmol liter' gibberellic acid (GA); (4) treated with 0.02 mol liter-' KNO3; (5) treated with dry heat (1300 C) for 3, 6,9, 12, and 15 minutes, (6) mechanically scarified; and (7) moist prechilled at 3 and 70 C for 2 or 4 weeks. Seeds were germinated in controlled environment chambers at 300 C. Germination was not enhanced by chemical scarification or rinsing. GA (1.4 mmol liter-) increased germination from 35% for controls to 61%. Mechanical scarification and dry heat enhanced germination of highly dormant seeds only. A 2-week moist prechill at 30 C increased germination of intact seeds from 6% for controls to 36%. Percent and rate of germination were similar among seed sources. Apparent afterripening requirements limited germination at 2 months after harvest to 3%. This requirement gradually broke down until at 8 months after harvest, germination had increased to 40%o. Our results indicated that treatment with 1.4 mmol liter-' GA or higher concentrations, moist prechilling for 2 weeks at 30 C, and storage for 8 months will increase germination of dormant anacua seeds. Authors are faculty researcher and research fellow, Caesar Kleberg Wildlife Research Institute, Campus Box 218, Texas AI and area manager, Las Palomas Wildlife Management Area, Texas Parks and Wildlife Department, 4200 Smith School Road, Austin, Texas 78744. Research was funded by the Texas Parks and Wildlife Department and The Caesar Kleberg Foundation for Wildlife Conservation. Authors wish to thank Dr. R. Bingham for his assistance in statistical analyses. Manuscript accepted 16 December 1985. Anacua [Ehretia anacua (Teran & Berl.) I.M. Johnst.] is a native, semievergreen shrub or small tree of the Boraginaceae that occurs in river valleys and bottomlands in central and south Texas southward into Mexico (Vines 1960, Correll and Johnston 1970). Anacua fruits are eaten by many birds and mammals (Vines 1960), and it is highly favored as a nest site by white-winged doves (Zenaida asiatica L.) (Brown et al. 1977). About 95% of the original brushland of the Lower Rio Grande Valley has been lost to cultivation and other land use practices. State and federal wildlife agencies are attempting to restore habitat for white-winged doves and other wildlife on former cropland in this region. Anacua is one of five woody plants considered to be of primary importance in habitat restoration. Other important species include spiny hackberry (Celtis pallida Torr.), bluewood (Condalia obovata Hook.), huisache [Acacia farnesiana (L.) Willd.], and Texas ebony [Pithecellobium flexicaule (Benth.) Coult.]. Low germination resulting from seed dormancy has hampered efforts to establish anacua. Alaniz and Everitt (1980) reported that the optimum temperature for anacua germination is 300 C. Seeds had to be soaked for 2 hours in concentrated sulfuric acid for appreciable germination to occur. Objectives of this study were to determine (1) additional methods of enhancing germination of anacua seeds and (2) possible causes of seed dormancy.

Light Requirements of Acacia smallii and Celtis laevigata in Relation to Secondary Succession on Floodplains of South Texas

Acacia smallii, a legume, is a pioneer woody species in secondary succession of floodplain forests of S Texas, where Celtis laevigata is the climax forest dominant. Variable light regimes, under greenhouse conditions, showed that A. smallii had its maximum growth in the highest irradiance and decreased growth occurred with decreased irradiance. Celtis laevigata showed no significant differences in growth between the two highest irradiances used. Interspecific comparisons based on percent of maximum growth indicated C. laevigata had a significantly higher percentage of maximum growth in lower light treatments, whereas A. smallii had a significantly higher percentage of maximum growth in the highest light treatment. Acacia smallii is a heliophyte, while C. laevigata is a sciophyte. Loss of A. smallii in mature communities is probably due to inability of its seedlings to survive in the shaded environment of a mature forest community. INTRODUCTION Plant response to light has long been recognized as an important factor which determines species replacement in forest succession (Bazzaz, 1979). Most studies have investigated species involved in old-field succession of the eastern United States, i.e., pine to oak-hickory forests. Kramer and Decker (1944) studied the pioneer woody species, Pinus taeda, and two hardwoods (Quercus alba and Q. falcata) which replace the pine. They showed that photosynthesis of P taeda increased with light intensity to full sunlight levels, whereas photosynthesis of the hardwoods increased rapidly up to a maximum rate at approximately 10% of full sunlight and then remained constant at higher light intensities. Subsequent studies examined the light requirements of a wide variety of species involved in old-field succession (Bazzaz, 1979); however, we have not identified any studies that dealt with woody legumes which have dominant roles in secondary succession in S Texas. Comparisons among secondary successional communities in the South Texas Plains region showed that the legume, Acacia smallii, is a dominant pioneer tree species on floodplain sites (Van Auken and Bush, 1985). Acacia smallii had the greatest basal area of all species in stands 15-30 years old; however, it declined in stands older than 30 years, as Celtis laevigata, the terrace climax forest species, increased in basal area (Van Auken and Bush, 1985). Acacia smallii is a presumed nitrogen fixer (Van Auken and Bush, 1985) and plants capable of fixing atmospheric nitrogen are often present early in succession (Stevens and Walker, 1970). Little is known about why these plants decline in later stages. The purpose of this study was to compare the growth response of Acacia smallii and Celtis laevigata at various light levels to test the hypothesis that differences in shade tolerance account in part for the observed successional pattern.

Fertilization Response of Early and Late Successional Species: Acacia smallii and Celtis laevigata

The sequential dominance of Acacia smallii and Celtis laevigata during secondary succession may be explained in part by examining the nutrient requirements of these two species. Acacia smallii has a low soil N requirement, while C. laevigata has a high soil N requirement. Growth of A. smallii and C. laevigata seedlings on amended soil was determined in a greenhouse experiment by measuring the increase in number of leaves, leaf length, plant height, and biomass. Using a factorial design with N and a complete nutrient supplement minus N, we determined that A. smallii biomass was stimulated 1.35-fold by the addition of mineral nutrients minus N, but it was not stimulated by N. Celtis laevigata biomass increased 5.6-fold with the addition of NH4NO3 but not with the addition of other nutrients.

Diurnal courses of leaf conductance and transpiration of mistletoes and their hosts in Central Australia

In Australia, diurnal courses of leaf conductance and transpiration of hemiparasitic mistletoes (Loranthaceae) and their hosts were measured using steady-state porometers under conditions of partial drought and high evaporative demand. The sites spanned a diversity of climatic regions ranging from the subtropical arid zone with winter rainfall, through the subtropical arid zone with summer rainfall to the tropical summer rainfall zone. With one exception (Acacia farnesiana with deciduous leaves), the hosts were trees or shrubs with evergreen, sclerophyllous leaves or phyllodes.The measurements confirm previous observations that mistletoes transpire at higher rates than their hosts. For adult leaves from all of the 18 different host/mistletoe pairs investigated, the daily average leaf conductances were higher in the parasites than in their hosts. The ratios ranged from 1.5 to 7.9. In the most extreme case,Amyema maidenii had a daily rate of water loss 8.9 times higher than its hostAcacia cowleana. Hoever, the parasites did not exhibit unlimited transpiration. Despite high water loss rates, leaf conductance showed large and consistent changes during the course of the day, indicating definite stomatal regulation. The typical diurnal pattern of conductance in both mistletoes and hosts consisted of an early morning peak followed by a continuous decrease throughout the remainder of the day. There was no abrupt decrease in leaf conductance of the parasites that might be interpreted as a threshold response with respect to internal water potential. In most cases, the continuous stomatal closure occurred without substantial changes in leaf water potential over a time span of several hours. The decrease in leaf conductance was correlated with an increase in leaf-to-air water vapor difference, which was associated with increasing leaf temperatures. It seems probable that external humidity plays a major role in the stomatal response. Diurnal courses of leaf conductance of the host/parasite pairs usually showed similar general patterns, even when the absolute rates were quite different. Thus, mistletoes not only control their water loss by stomatal action but this regulation seems to occur in coordination with the stomatal response of their hosts.The integrated mistletoe/host system must also endure severe drought conditions. Controlled water use is necessary for long-term survival of the host. Assuming stomatal behavior in the host is well adapted to ensure its existence, then similar performance in the mistletoe would promote survival of both host and parasite.

Brush Response to Spacing and Individual-Plant Herbicide Treatments

Soil-applied herbicides were evaluated for control of blackjack oak (Quercus marilandicaMuenchh.), huisache [Acacia farnesiana(L.) Willd.], honey mesquite [Prosopis juliflora(Swartz) DC. var.glandulosa(Torr.) Cockerell], live oak (Quercus virginianaMill.), Macartney rose (Rosa bracteataWendl.), winged elm (Ulmus alataMichx.), and yaupon (Ilex vomitoriaAit.) in Texas. Various spacing of spot treatments of pelleted tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} on huisache and live oak and picloram (4-amino-3,5,6-trichloropicolinic acid) on Macartney rose up to a 2.7-m square grid did not change herbicide effectiveness. Pelleted tebuthiuron at 2.2 kg/ha reduced the canopy of live oak and killed a significant percentage of plants; however, differences among herbicide formulations and distance of placement in a grid were small. On unburned plots, 2.2 kg/ha of tebuthiuron applied as pellets at 2.7-m centers and as a broadcast wettable-powder treatment killed fewer yaupon than pellets applied in most broadcast treatments. In individual-plant treatments, bromacil (5-bromo-3-sec-butyl-6-methyluracil) and picloram solutions at 2 g/plant killed 45% of the yaupon 1.5 to 2 m tall on a fine sandy loam, whereas 0.5 g/plant of either herbicide killed 70% or more of the yaupon plants 1 m tall on a loamy fine sand. Both bromacil and picloram at 1 g/plant killed all blackjack oak and winged elm sprouts 1 to 2 m tall. On a clay soil, 1 g of bromacil/plant killed 79% of the live oak and 88% of the winged elm plants, whereas picloram killed only 38 and 45%, respectively. Neither bromacil nor picloram was effective as soil treatments for killing honey mesquite.

Notes on Cerambycidae Co-Inhabiting Girdles of Oncideres pustulata Leconte (Coleoptera: Cerambycidae)

Nineteen species of cerambycid beetles found co-inhabiting Tepehuaje (Leucaena pulverulenta, Fabaceae) girdled by adult Oncideres pustulata LeConte at the Sabal Palm Grove Sanctuary, Cameron County, Texas, USA, are listed and their habits briefly discussed. Literature concerning cohabitation of 0. pustulata girdles by other longhorned beetles is reviewed. Charac- ters for separating larvae of 0. pustulata and the closely-related Lochmaeocles c. cornuticeps (Schaeffer) are enumerated. Other insects associated with 0. pustulata-girdled Tepehuaje include 14 species in the beetle families Buprestidae, Curculionidae, Bostrichidae, Tenebrionidae, Mordel- lidae, Trogositidae, Cleridae; and the Tineidae (Lepidoptera). The cerambycid beetle Oncideres pustulata LeConte, commonly referred to as the Girdler, is distributed widely in southern Texas and northern Mexico, where it breeds in a variety of leguminous (= Fam. Fabaceae) trees and shrubs. Adults create suitable larval habitat by girdling the trunks of sapling-size trees or the distal portions of branches of larger hosts. Such girdling can be quite destructive, and 0. pustulata occasionally has been considered a pest of some economic significance. Bionomical information has been presented by High (1915) (as 0. putator Thomson), Linsley and Martin (1933), and Vogt (1949). Dead and dying Oncideres-pruned branches provide an equally suitable habitat for other phytophagous insects, and numerous opportunistic species of cerambycids have been recorded as utilizing these girdles. Craighead (1923) described the larvae of Geropa concolor (LeConte) (as Achryson con- color) and Neocompsa mexicana (Thomson) (as Ibidion townsendi Linell) from 0. pustulata-girdled Huisache (Acacia farnesiana (L.) Willd.). These two beetles and four others, Neocompsa exclamationis (Thomson), Obrium maculatum (Olivier), Neoclytus acuminatus (presumably subspecies hesperus Linsley,) and Anelaphus sp., probably debilis (LeConte) (as Anoplium trun- catum LeConte), were reared from girdles of Huisache and Ebony (Pithecel- lobium flexicaule (Benth.)) by Linsley and Martin (1933). Six additional spe- cies later were recorded from several genera of legumes by Linsley (1940): Placosternus difficilis (Chevrolat), Euderces (reichei) exilis Casey, Ecyrus arcuatus (Gahan) (as E. texanus Schaeffer), Sternidius wiltii (Horn), Sterni- dius mimeticus (Casey) (as Leiopus houstoni Casey), and Sternidius texanus (Casey) (as Leiopus texanus). (Dillon (1956) placed texanus as a synonym of mimeticus; the type of texanus is, however, quite distinct from that of mime- ticus. Further study may show texanus to be a synonym of either S. naevii- cornis (Bates), from Mexico, or the widespread S. alpha misellus (LeConte)). Vogt (1949) increased the number of associated species to 16 with the addi- tion of Stenosphenus lugens LeConte, Lissonotus flavocinctus puncticollis Bates, Thryallis undatus Chevrolat and Lochmaeocles c. cornuticeps

Hexazinone and Other Herbicides on Texas Woody Plants

Hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] was applied to honeylocust (Gleditsia triacanthosL.), honey mesquite [Prosopis juliflora(Swartz) DC. var.glandulosa(Torr.) Cockerell], huisache [Acacia farnesiana(L.) Willd.], live oak (Quercus virginianaMill.), Macartney rose (Rosa bracteataWendl.), post oak (Quercus stellataWangenh.), saw greenbrier (Smilax bona-noxL.), whitebrush (Aloysia lycioidesCham.), and yaupon (Ilex vomitoriaAit.). Bromacil (5-bromo-3-sec-butyl-6-methyluracil) and tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} were used for comparison in some experiments. Hexazinone was required at the following rates to kill at least 75% of the following species: 1.1 kg/ha for live oak, 2.2 kg/ha for post oak, 4.5 kg/ha for huisache (at Bryan, Texas) and whitebrush, and 9 kg/ha for honeylocust. Hexazinone was ineffective at 9 kg/ha for control of honey mesquite, huisache (at Washington, Texas), Macartney rose, saw greenbrier, and yaupon. Tebuthiuron at 1.1 kg/ha killed 80% of the live oak, and as a subsurface spray at 4.5 kg/ha, killed huisache (at Washington, Texas). Bromacil was effective on huisache at 9 kg/ha.

Control of Whitebrush (Aloysia lycioides) and Associated Species with Soil-Applied Herbicides

The responses of whitebrush (Aloysia lycioidesCham.) and several associated species to herbicides were evaluated in the Central Basin and South Plains of Texas. At Llano, hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione], picloram (4-amino-3,5,6-trichloropicolinic acid), and tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} were the most effective herbicides for whitebrush control. Picloram was the most effective herbicide on Lindheimer pricklypear (Opuntia lindheimeriEngelm.), tasajillo (Opuntia leptocaulisDC.), Texas colubrina [Colubrina texensis(Torr. & Gray) Gray], and Texas persimmon (Diospyros texanaScheele). Hexazinone, karbutilate [tert-butylcarbamic acid ester with 3(m-hydroxyphenyl)-1,1-dimethylurea], and tebuthiuron controlled live oak (Quercus virginianaMill.). Tebuthiuron pellets were slightly more effective on whitebrush when applied broadcast than when applied in rows 1.8 to 6.0 m apart. Roller chopping alone did not kill whitebrush nor improve effectiveness of tebuthiuron but did improve access to the land and visibility for 3 yr. Picloram applied either as the undiluted liquid formulation or as granules was the most effective herbicide for controlling a spectrum of species, including whitebrush. Picloram pellets were generally more effective on Lindheimer pricklypear and Texas persimmon when applied broadcast than when applied in rows. However, tebuthiuron was the most effective herbicide on blackbrush acacia (Acacia rigidulaBenth.) and huisache [Acacia farnesiana(L.) Willd.], especially when applied in rows rather than broadcast.

Seasonal constancy of intra-population variation of HCN content of costa rican Acacia farnesiana foliage

The HCN content of dried Acaciafarnesiana foliage varies from 0.0 to 5.49 μmol/g among individuals within a population ( X = 1.80, s.d. = 1.80 in wet season; X = 1.21, s.d. = 1.27 in dry season; n = 26) and increased in the wet season (average difference of 0.59 μmol/g) in Santa Rosa National Park, Guanacaste Province, Costa Rica. The correlation coefficient of HCN values for 26 bushes in the wet and the dry season was 0.898, suggesting that the seasonal change was proportional to the amount of HCN present in the foliage of each bush.

Distribution of Triclopyr and Picloram in Huisache (Acacia farnesiana)

The triethylamine salt of triclopyr [(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid and the potassium salt of picloram (4-amino-3,5,6-trichloropicolinic acid) were applied as soil, foliar, and soil-plus-foliar treatments to greenhouse-grown huisache [Acacia farnesiana(L.) Willd.]. At 1.12 kg/ha, picloram was more effective (97 to 100% defoliation) than triclopyr (51 to 83%) in defoliating huisache. Triclopyr was more effective at 2.24 kg/ha than at 1.12 kg/ha in defoliating huisache, except when applied to the soil. Soil or soil-plus-foliar treatments of triclopyr at 2.24 kg/ha were not significantly different from those of picloram at 1.12 kg/ha 15 weeks after treatment. Triclopyr and picloram content was determined in and on leaves, stems, and roots at 0, 3, 10, and 30 days after treatment. More picloram than triclopyr was found in the leaves 30 days after treatment with foliar sprays at equal rates. Soil, foliar, and soil-plus-foliar treatments resulted in greater accumulation of picloram than triclopyr in stem tissue. Herbicide concentrations in roots were usually low. Reasons for the greater herbicidal activity of picloram than of triclopyr in huisache are not clear; however, the greater accumulation of picloram than of triclopyr in leaf and stem tissue may partially explain the difference in herbicide activity.

Huisache Control by Power Grubbing

Huisache Control by Power Grubbing

Germination Response of Some Woody Plant Seeds to Electrical Treatment

Seed lots of Macartney rose(Rosa bracteataWendl.), yaupon(Ilex vomitoriaAit.) huisache [Acacia farnesiana(L.) Willd.], and honey mesquite [Prosopis juliflora(Swartz) DC. var.glandulosa(Torr.) Cockerell] were exposed for various periods to radiofrequency (RF) dielectric heating by electromagnetic fields of 10 and 39 megahertz (MHz) at various field intensities in attempts to increase their germination. Both continuous-wave and pulse-modulated exposures were used at 39 MHz. Seed samples were preconditioned at temperatures from 24 to −43 C before exposure. Sixty-Hz a-c and d-c electrical treatments were included in some experiments. Although significant increases in germination were obtained by RF treatment of huisache and honey mesquite seed in some experiments, results with different huisache seed lots were inconsistent. The germination of Macartney rose seed was not increased, and no germination was observed in yaupon, regardless of the treatment employed.

Birds as Predators on the Brood of Polybia Wasps (Hymenoptera: Vespidae: Polistinae) in a Costa Rican Deciduous Forest

Birds as Predators on the Brood of Polybia Wasps (Hymenoptera: Vespidae: Polistinae) in a Costa Rican Deciduous Forest

Cattle Egrets in Central Coahuila

On 23 February 1974 Sr. Ignacio Urutia shot a Cattle Egret (Bubulcus ibis) in his garden at Ocampo, an isolated village (elev. ca. 1100 m) in the Chihuahuan Desert of central Coahuila, Mexico (27?22'N, 102* 26'W). The bird appeared emaciated, and dissection revealed no fat. Flies were present in the stomach and completely filled the esophagus. The bird was an immature female with a yellow bill and nearly black feet. The ovary measured 7 x 12 mm. This is the first specimen of a Cattle Egret taken in Coahuila. It has been given to the Field Museum of Natural History, Chicago (FMNH #297139). Ocampo is in a basin surrounded by mountains ranging from ca. 780 to 2900 m. Characteristic plants of the region are creosote-bush (Larrea tridentata), lechuguilla (Agave lechuguilla) and prickly-pear cactus (Opuntia spp.). Mesquite (Prosopis sp.), huisache (Acacia farnesiana) and Acacia rigidula occur chiefly around water. Plants commonly cultivated and irrigated include maize, beans, alfalfa, and sorghum. Cattle Egrets were observed in Coahuila during 1974 as follows: on 19 February, Philip Weisheipl saw one bird flying low over our residence adjacent to Sr. Urutia's garden at Ocampo. This may have been the same bird shot four days later, as Cattle Egrets were not seen again in Ocampo for more than two months. Craig Cady and I saw 27 of these herons about 24 km NE Torre6n on 28 March. John L. Kaspar saw three near Monclova on 10 April. On 25 April, Sylvia Brey saw an immature egret with cattle just southeast of Ocampo. She and Cady observed one in the same plumage at the same site two days later. Brey found three egrets there on her last visit on 28 April. I elieve these sight records to be the first from the ce tr l part of Coahuila. Zimmerman (Condor 75:480-481, 1973) reported sight records of the species from Durango, San Luis Potosi, central Chihuahua, southern Nuevo Le6n and the Torre6n region of Coahuila. Contreras (Publ. Biol. Inst. Invest. Cient. Univ. Auton. Nuevo Le6n 1:2-3, 1973) reported a Cat le Egret collected on 5 December 1971 near the village of China in Nuevo Le6n. I thank John L. Kaspar for his assistance in organizing the manuscript.